Yeah, they have to be overlaps. Thats what I love, trying to see if I can get everything to "fit". I may not finish them all but it is a challenge!!! If I can't use overlaps I usually don't join. I'm not a super reader like some around here. I'll do the best I can and see how far I get.

The challeges also let me explore new areas. I guess I technically don't have to join but when I join I get to "meet" new people and see their blogs etc.

I might just have to join this challenge then! I can do overlaps. And I can make the historical one overlap as well. And I see what you mean about finding other blogs...I have no idea how I landed on half the ones that I read! Of course, blogging infringes on my reading time!